Today, a 2200-year-old age of invention. The
University of Houston's College of Engineering
presents this series about the machines that make
our civilization run, and the people whose
ingenuity created them.

Alexander the Great fell ill
and died in 323 BC. He was only 33. As a teenager
he'd studied with Aristotle. From the age of 16 to
20 he'd been the general who helped his father
Philip II unify Greece. Then Philip was
assassinated, and the armies made Alexander their
king. Over the next 13 years, Alexander had
conquered present-day Egypt, the Holy Land, Turkey,
and a swath eastward from there all the way to
Pakistan.

But these had been no ordinary conquests. Those
years with Aristotle had made a scientist of
Alexander. He extracted knowledge from foreign
lands and stirred Greek culture into theirs. He
worked very hard at mixing the cultures of East and
West -- at stimulating trade, cultural exchange,
and intermarriage.

His empire fell apart after he died, but the
effects of it were lasting. Of fifteen cities he'd
founded and named Alexandria, the one northwest of
Cairo emerged as the center of Mediterranean
culture. A new dialect of Greek, the Koinia,
became the common language of the Eastern
Mediterranean basin. The closed world of the
Hellenic city-states gave way to polycultural
Hellenistic civilization.

Alexandria drew talent like a magnet. Euclid,
Archimedes, and the astronomer Ptolemy all worked
there. The astronomer Eratosthenes accurately calculated
Earth's diameter. Alexandria remained the
intellectual center of the world for three
centuries -- until Octavian claimed Egypt for Rome
after Cleopatra's suicide in 30 BC.

The much-praised technology of the Romans was built
on inventions of the great Alexandrian engineers.
Plumbing, gearing, and water wheels all came from
Alexandria. Those Greco-African engineers had names
-- like Ktsebios, Philon,
and Heron (or Hero).

The most remarkable Alexandrian invention was
feedback control. A feedback device automatically
corrects the way a machine functions -- like our
thermostats, speed controllers and pressure
regulators. The Alexandrian engineers invented all
sorts of float valves and other liquid-level
regulators. The most important machine that used
these gadgets was the water clock. The Alexandrian
water clock was the basic time-keeper until the
mechanical clock replaced it around AD 1300.

Alexandria was free-wheeling, open, cosmopolitan,
and wonderfully inventive. After the authoritarian
Romans moved in, invention withered in Alexandria.
And no new use was made of feedback until a new
craving for freedom swept Europe in the middle of
the 18th century. But let's leave that for another day.

Other intensely creative civilizations have
surfaced throughout history -- the Court of
Baghdad, the High Middle Ages, nineteenth-century
America. All those epochs reinforce one inescapable
message about powerful creativity. They all show us
what free people, exposed to wide-ranging outside
influence, can do when they let their minds run
free.

I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
work.

(Theme music)

Clough, S., A History of the Western World,
Vol. I, Ancient Times to 1725. Boston: D. C. Heath,
1964.